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Hard Starting on Damp Mornings

I have a 2000 Hyundai Elantra that has 143K on it. It runs well, but if the weather is very damp, is hard to start. The starter turns at normal speed, but the engine doesn’t catch. It also bucks if you release the key from the start position. After several tries it successfully starts and after a minute or two smoothes out and runs fine (until the next time). The car was tuned up at 120K and I have replaced the fuel pressure regulator (torn diaphragm) and the ignition wires.

It does not seem to be the fuel pump bleeding down as leaving the ignition key in the run position for several seconds has no affect on it starting. Mileage has not been affected nor has drivability.

Any suggestions? The sensors that affect timing are $100 a piece, too dear to do a trial and error.

Also I checked with an OBD II reader and have no codes or pending codes.

Replace the spark plug wires.

Old, dried out spark plug wires are a common cause of starting difficulties in damp weather. The insulation cracks and allows the current to jump to ground. You can actually see this at night. It looks like tiny lightning bolts arcing from the wires to the engine block.

If this vehicle has a distributor you should probably replace the cap and rotor, too.

I agree with McP.

If these parts don’t fix it, consider also the coil pack. These can become sensitive to moisture also with the years.

With brand new wires, I was guessing on either the cam shaft position sensor or the coil pack. In searching the auto parts houses it seems like the coil pack is in stock and the cam shaft sensor a special order item. I’ll see if I can find diagnostics for it, there must be a way to test it that doesn’t cost $100. Thanks.

See if the coil pack comes with a return policy. If so, you can probably get a refund if it doesn’t fix the problem. It’s an easy R&R.

It would have been nice if you’d said “brand new wires.”

How are we to know?

Problems when damp goes to “plug wires” and plugs. Coil packs break down with heat and are not usually that sensitive to moisture.

The quality of replacement spark plug wires varies greatly. The wires may be new, but they might not be good. How long have the plugs been in the car? With only 23K miles the plug may not be showing a worn gap but it could be breaking down where the gasket seals the ceramic insulator in the metal base. Moisture at the base of an old plug can short out the plug and cause some misfires when starting in moist conditions.

I’d suggest another brand of plug wires and some new plugs.

I like the idea of fuel injector testing with the possibility of a helping out. I question the linking of symptons to damp weather. have you always been using Top Teir fuel? you should be.

I have got new Autolite pro series wires in it now(less than two weeks old), the problem goes back for a while (10 or more K miles). This set of wires was my latest attempt. The previous set of replacement wires were off brand and broke down. I pulled the plugs and they look fine. As for F.I. cleaner, I use it regularly and never use off brand fuel. The plugs may have broken down, but they are NGK Platinum and if they were at fault I would think they would be DOA after failing that long. At least that is something I can try. As for returning the coil pack, most auto parts houses I have done business with don’t accept returns on electronics, I guess I could check that out with the place I am doing business with now.

I now believe I have found the problem, but only time will tell. The last time the car was hard to start that the old wire set was still in place, I ‘cured’ the problem by moving the plug wires in the coil pack towers. Today I removed the new wires from the same side and found what looks like patina on the connectors in the tower. I suspect the old wire boots weren’t doing their job. I cleaned them and reinstalled the new boots being sure that they went all the way down.

Thank you all for the suggestions. Hopefully this will be the end of this.